Segmented belt

ABSTRACT

A flexible belt formed of hinged segments with two or more segments and preferably separated by spaces. The belt is formed of a suitable plastic, such as an elastomer of the polyurethane type. On one side of each segment there are short integral hollow cylinders and mating cylinders on the other side. When two units are placed together the hollow cylinder portions meet to form a substantially complete cylinder in the same manner as a series of hollow cylinders in a hinge for a door. A pin, such as a more or less rigid nylon pin, is passed through the cylinders of the units to form a hinged structure, and this is repeated until endless flexible belts are produced. The units have flat surfaces abutting opposite flat surfaces at the joint, which prevents the hinge opening any substantial amount. The belts are principally useful as snowmobile treads but are also effective for power transmission or for conveyors. The belts are provided with suitable openings or projections which can engage pulleys or sprockets for drive purposes. Some flexibility in each unit is necessary to give the desired belt contour.

United States Patent [72] Inventors Ralph A. Maglio Westhnmpton; DonaldN. Russell, Easthampton, both of, J Mass. 1 [21] Appl. No. 843,595

[22] Filed July 22, 1969 [45] Patented Aug. 31,1971 [73] Assignee J. P.Stevens 8: Co.. Inc.

New York, N.Y.

541 SEGMENTED BELT 16 Claims, 12 Drawing Figs.

[52] U.S.Cl 198/193,

[51] Int. Cl ..B65g 15/30, 862d 55/08 [50] Field of Search 198/195,

FOREIGN PATENTS 824,043 9/1968 Canada 305/38 462,126 6/1928 Germany305/38 ABSTRACT: A flexible belt formed of hinged segments with two ormore segments and preferably separated by spaces. The belt is formed ofa suitable plastic, such as an elastomer of the polyurethane type. Onone side of each segment there are short integral hollow cylinders andmating cylinders on the other side. When two units are placed togetherthe hollow cylinder portions meet to form a substantially completecylinder in the same manner as a series of hollow cylinders in a hingefor a door. A pin, such as a more or less rigid nylon pin, is passedthrough the cylinders of theunits to form a hinged structure, and thisis repeated until endless flexible belts are produced. The units haveflat surfaces abutting opposite flat surfaces at the joint, whichprevents the hinge opening any substantial amount. The belts areprincipally useful as snowmobile treads but are also effective for powertransmission or for conveyors. The belts are provided with suitableopenings or projections which can engage pulleys or sprockets for drivepurposes. Some flexibility in each unit is necessary to give the desiredbelt contour.

PATENTED M1631 |97| SHEET 1 BF 6 INVENTORS RALPH A M461. /0

DONALD IV. RUSSELL A TTOR/VEY PATENTED aussl I971 3.602.364

SHEET 2 [1F 6 \lm lkwnllwNvmmmvm INVENTORS, RALPH A. MAGL/O DONALD N.RUSSELL A T TOR/V5 Y SHEET 3 BF 6 INVENTORS. RALPH A. MA 6L /0 BY DONALDN. RUSSELL ATTORNEY PATENTEU Aussl I971 p .1 i i viwmimmmmwww H M IQMPATENTEDAUB31I971 3.602.364

sum u UF 6 'IIJIIN'A. L r

INVENTORS. RALPH A.MA6L/0 F H DONALD M RUSSELL A TTORNEY PATENTEU M1SHEET 5 BF 6 INVIz'N'l'ORS. RALPH A. MAGL/O DONALD N. RUSSELL A TTORNEYPATENTEU was] 1971 3502 3554 sumsnre INVEN'I'ORS. RALPH A. MAGL/O DONALDRUSSELL ATTORNEY like, which may be either solid or reinforced withfabrics, such SEGMENTED BELT BACKGROUND OF THE INVENTION Endless beltsof elastic or other material with suitable projections forming cleatsare used on snowmobiles as the driving track. Many problems arepresented because of stretch and the like, expense of moldingcomplicated shapes, and'ot'her problems.

Tracks of hinged metal segments have also been used for military-tanks,crawler tractors, and the like. They are heavy and unsuitable for use asbelts which must have additional flexibility. Also, as there is noelastic give to the tracks, segmented rail elements must be provided onwhich a large number of bogie wheels can run. This is, of course,unsuitable for most snowmobile work where generally two sprockets areused with a flexible portion of belt between them.

' It has also been proposed to prepare segmented conveyor belts withthe-segments fastened with pins to form integral, molded roller chainswhich fit in sprockets. This, however, is quite expensive and is notsuitable for many uses, such as snowmobiles.

SUMMARY OF THE INVENTION The present invention utilizes an elasticconstruction in which endless belts are made with hinged segments ;ofelastomeric material, such as rubber, polyurethane, and the as textilefabric, glass fibers, metal wires, and the like, so that a cross sectionthrough a hinged segment of each belt resembles part of a door hinge.The number of belts which are formed of the segments are two or more,preferably at least three. ln the general description to follow aswellas specific description of drawings, an invention in which the belthas'three endless belts will be described as a typical illustration,though of course the invention isnot limited to this exact number ofendless belts when the invention has been assembled. Each belt resemblesa part of a door hinge. The belts may be of segments which extend acrossthe full width of the belt, but for many purposes, particularly forsnowmobiles tread use, the segments form two or 'more, for examplethree, individual belts separated by spaces which constitute slots andcan grip sprockets for driving purposes; In snowmobiles treads thespaces also" perform the important function that they permit snow tofall through, and the problem of snow packing on a snowmobile track isavoided. Y

The nature of the elastomeric plastic of which the belt segments aremade can vary and will depend in'large measure on the use to which thebelt is to be put. As flexibility is desired, the elastomer should havea sufficient stretch, and in the case of snowmobile treads they mustremain reasonably elastic at quite low temperatures. Among thematerials, polyurethanes are particularly important although oilextended rubber, polyepichlorhydrin, and the like may be used. Ingeneral, thedesired properties will dictate to a large extent thechemical and physical properties of the elastomer used. For example,

elastomer. Two generaltype's of chain extenders are in use,

namely diamines and diols. Atypical example -.of ahindered diamine, is4, 4' amino 3, 3"chlorodiphenylmethane. This diamine is generallyreferred to in the trade as Moca, and for brevity this abbreviation willbe used in the present specification. The most common diol extender isl, 4 butane diol. The invention is in no sense limited to these typicalextenders and other well-known extenders may be used. Forsnowmobiletread work there is some advantage in using Moca. In general, the.nature of the final polyurethane elastomer contains only polyurethanegroups when diol extenders are used but alternate the polyurethanegroups with ureas when diaminesare employed. The amount of extender usedwill vary, for example from about '90 percent of the free NCO groups inthe prepolymer to 100 percent or slightly over, such as 102 percent,depending on the particular properties desired. Where there is anextension of somewhat over 100 percent, of course this means that thereis some free extender present in the final elastomer, which has acertain plasticizing effect. In general the present invention is not inany way limited to the particular elastomer, and the ones mentionedabove are merely illustrative. Because of the fact that the propertiesof the polyurethaneelastomers are superior and they are usuallypreferred to other elastomers, such as the rubbers andpolyepichlorhydrin, the rest of thedescription will ,deal primarilywiththe preferred polyurethanes, it being understood that the invention isin no sense limited to the use of these particular elastomers. IngeneraLall of the elastomers used are in themselves well-known types,and in the more'specific disclosure there will be given only a singleillustrative example of a typical polyether based, diamine extendedpolyurethane. When polyurethanes are used, the normal two-step processwith the formation of the prepolymer with excess NCO group followed bychainjextensioncan also be modified by usin'gsingle step processes, forexample those in which a diamine is blended with the particularpolyether used and then reacted with the diisocyanate. Satisfactoryproducts can be made by this process but the pot life is very short andthe manufacturing control is, therefore, more critical because thematerial has to be molded or cast within 10 or 15 minutes after theformulation, and therefore it is ordinarily desirable to producepolyurethanes by the more customary two-step procedure. It should benotedthat as with all known polyurethanes the cast for snowmobiletreads, in order to retain stretch and flexibility at' very lowtemperatures the resin buildings blocks, if

polyethers, must not be of too low molecular weight, otherwise theresulting polyurethane becomes too stifi' and even. brittle at lowtemperatures. Polyester based polyurethanes are also usefuL-and ingeneral the present infintion is not limited toany particularpolyurethane composition so long as ithas the needed physicalproperties.

In general polyurethanes are prepared in two steps,'by first forming aprepolymer with the building block resins and as exelastomer proceedstocross-link somewhat further, for example by atmospheric moisture, andthis curing increases the strength and the abrasion resistance of theproduct. Here again, this is nothing new as these procedures are more orless standard practice in producing polyurethane-elastomers, and it isan advantage that the present invention in not limited'to a particular,precise operating procedure.

For many purposes, for example some conveyor belts and snowmobilestreads, the straight elastomer is usable. Where, however, greaterstrength is required there may be fibrous reinforcements, such as nylonfabric, glass fibers, or glass fiber fabrics, metal wires, and the like.In such a case a cross section through a hinged segment of a beltresembles that of a tire.

Itwill be noted that in general the endless belts are made more flexibleby the hinge construction with suitable cutouts so that the hinge canbend through a considerable angle. However, the flexibility of theelastomer is sometimes sufficient and the stretchability or bendingconfers sufficient flexibility, particularly where sprockets, pulleys,or other elements do not have too small a radius of curvature. Wherethere are no cutouts in the segments the belt presents a practicallyunbroken surface, which is of importance for some uses, such-as conveyorbelts. These belts are also somewhat stronger and may be more suitablefor certain power transmission uses where slippage andexcessive beltstretch is undesirable. The segments are also useful for other types ofstructure, for example I Conveyor belts present two different kinds ofproblems. In some cases it is desirable that the outside, which formsthe actual conveyor surface, be relatively smooth. In this case thesegments have no ridges or cleats and preferably extend across the fullwidth of the belt. Such smooth surface conveyor belts are useful wherethey convey materials such as packages, containers to be filled, and thelike which may have to be bunched together by intermittent barriers orslid off to the side by deflectors. One problem which arises with theconveying of relatively small sizes of materials, such as sand, coal,and the like, is preventing slippage off the edges of the belt, whichcan be provided with segments having edge lips molded in. With someconveyors it is, however, desirable to provide against slippage of thematerials being conveyed, for example packages and the like. Inserts inthe form of suction cups and the like may be molded in or may beinserted in suitable holes in the segments where they are to be ofdifferent material, such as, for example, a much softer elastomer.

For snowmobile tread use it is sometimes desirable to provide forincreased traction on ice as the snowmobile may leave ordinary packedsnow and traverse certain areas of ice on which the ordinary ridges orcleats do not give sufficient traction, or in the case of smooth ribsacross the width of the belts, may actually act as sled runners and socome out sideways, skidding. In such cases holes may be present whichcan be filled with suitable hard inserts, such as tungsten carbide studsof the type often used in the treads of snow tires.

Not only does the present invention permit the production economicallyof very desirable-flexible belts, but the hinged construction providesthe enormous advantage that segments can be changed. For example, in thecase of a snowmobile track, the track may become torn, and when thisoccurs there is a very serious problem presented because the ordinarysnowmobile endless track has to be mounted over sprockets,

either driving or idling, and this requires in many cases an actualmechanical adjustment of the spacing of the sprockets to permit a newbelt to be inserted over them. In the extremely hostile environment ofcold, winter weather and snow in which the vehicle is often used, thiscan not only be timeconsuming but can be extremely uncomfortable. Also,in any event, it requires carrying spare tracks, which are quite bulkyas the whole track, has to be carried. In the case of the presentinvention, however, it is sufficient to carry a few segments andfastening pins, and repair can be made quickly and easily by replacingworn or torn segments. This possibility also has another advantage wherethe nature of the surface on which the snowmobile is to be used changes.For example, if icy patches are to be encountered it is not necessary tohave an entirely new track with carbide studs; it is possible to inserta few studded segments, which will give sufficient traction and whichcan be rapidly and easily inserted and compactly stored on the vehicle.

Another advantage of the segmented character of the belt is encounteredwhere belts of varying length are to be produced. Where endless beltswere molded or cast in the past, special equipment had to used for eachlength of belt. With the present invention very simple castings ofsegments can be made and belts of any length desired can be assembled bypinning together the desired number of segments. In many cases thisrepresents an important manufacturing advantage which reduces the costof equipment as well as making it unnecessary to store large numbers ofbulky belts or tracks of different lengths. The segments, of course, canbe stored and transported compactly and assembled into belts or tracksof any desired length.

The hinge construction of the segments of the present inventionrequires, of course. that there be cylindrical hollows molded in. This.however, presents no problem as molding with suitable mandrels is acommon procedure in the art and well-known equipment can be used.

The pins employed in the belts according to the present invention may beof various kinds. For example, they may be metal rods, and for certainconveyor belts this permits obtaining great strength with a simpleconstruction. However, for

many, uses, particularly for snowmobile tracks, pins of nylon or otherstrong plastic are usually preferred. Retention of the pins during useis often no serious problem as the friction when a nylon pin is forcedthrough the hollow cylinders of the segment is often sufficient.However, where a maximum of protection against sideways movement of thepins is desired, the end cylinders of each segment may be provided withan enlarged portion and a pin, such as a nylon pin, can be expanded intoit. which prevents any loss of pins. This makes it somewhat moredifficult to replace segments in the field, for example under the harshconditions of use of a snowmobile, and for these uses often theunexpanded pins have adequately tight fit and present the advantage thatit is a fairly easy matter with suitable tools to remove a pin or toinsert a new one.

Where reinforcement is used, such as nylon fabrics, glass fiber fabrics,and the like, normally the reinforcement is needed only in the flatportions of the segments because these are the thinnest portions, thepins reinforcing the hollow cylinders at the edges, and these portionsare also thicker in any event. It is much easier to mold in reinforcingmaterial into a flat portion of a segment, and such reinforcement isnormally more than adequate to confer the desired additional tensilestrength. Where reinforcement is desired, the reinforcement of the flatportions of the belt segments may, therefore, be considered as apreferred form. Where unwoven fibers are used they may be mixed with thepolymer prior to molding.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric of trackcomponents with cleats;

FIG. 2 is an isometric of complete assembled track;

FIG. 3 is an elevation and partial section through hinge showing pinassembling two components and broken away areas showing reinforcingfabric;

FIG. 4 is an isometric of a modified form of track components, whichwill be referred to briefly as new in contradistinction to the olderform of track shown in FIGS. 1 to 3;

FIG. 5 is an isometric of partial assembly of new track;

FIG. 6 is an elevation and partial section through hub showing pinassembling two components and broken away areas showing reinforcingfabric;

FIG. 7 is an isometric of new track for conveyor use illustrating aportion with smooth segments and a-portion with segmentshaving suctioncups inserted to prevent slipping on the conveyor;

FIG. 8 is an elevation of a new truck with smooth segments for use as aconveyor or power transmission belt;

FIG. 9 is an isometric of a new snowmobile track with carbide studs;

FIG. 10 is an isometric of segments to be used for Quonset huts;

FIG. 11 is an isometric of a Quonset hut, and

FIG. 12 is an isometric of old tract to be used as a column or antennamast.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the varioustypes of belts shown in the drawings, the following typical polyurethaneformulation will be described and is useful in all of the specificstructures, although, as had been stated above, the invention is in noway limited to any particular single formulation. A prepolymer is formedwith-polypropylene glycol of approximately average molecular weight of2,000, although lower molecular weight glycols may be used where maximumhardness and strength is desired and low temperature flexibility is lessimportant. A prepolymer of the glycol and TDl with a ratio of NCO to OHof from l.75:l to 2:1 is formed at about C., using suitable protectionagainst oxidation, for example by providing a nitrogen atmosphere. Mocais the added in an amount to provide a ratio of NH of 1:1, in otherwords percent extension. Somewhat lower extensions give softermaterials. The prepolymer and diamine are brought together in a castingsystem using standard commercial casting machines. The pot life is aboutminutes. Molding times are approximately to 30 minutes, followed by anaftercure of about 1 hour at 100 C. Additional curing takes place atroom temperature, and at 22 hours a compression set at 150 F. shows offrom 20 to 30.

1 Two general types of segmented belts or structures are described inthe drawings. The first, which is shown in FIGS. 1 to 3 and 12, has somecutouts in the flat portions of the segments so that when fastenedtogether with pins, as will be described, the hinges formed can bendthrough a fairly large angle and belts or tracks of maximum flexibilityresult. FIGS. 1 to 3 illustrate a typical snowmobile belt or track inwhich the segments unite to form three transversely connected endlessbelts with spaces between them. The segments have flat portions 1 onwhich are integrally molded cylindrical elements 2 and 3. They are ofdifferent sizes, on one side a longer piece bridges the spacing betweenthe flat segment and on the other side there are shorter cylinders 3which fit into the spaces between the cylinders 2 when the segments areabutted. When this occurs, as can be seen best in FIG. 3, there is ahollow cylinder formed through which a pin 4 is introduced. In theexploded view of FIG. 1 and in the isometric of the whole assembledsnowmobile track, FIG. 2, the pins are shown partly inserted. In thecase of FIGS. 1 and 2, the pins are smooth and are held in by frictiononly once they are inserted. One end cylinder 5 is closed so that thepin cannot stick out once inserted fully. In FIG. 3 the top shortcylinder 6 is shown with an enlarged recess 7, and the pin, after fullyinserted, is expanded into it. This is effective with pins which aresomewhat deformable, for example nylon pins. In FIGS. 1 and 2 the pinsare not expanded as the upper short cylinders are the same as the centerone and therefore numbered 3 in FIGS. 1 and 2. In all of the threefigures the cylinders 2, 3, 5, and 6 are shown with cleats 8 on theirprotruding surfaces, which increase the traction of the whole snowmobiletrack, as can readily be seen in FIG. 2. These cleats are slightlyinclined to give protection both against sideways skidding and alsoforward traction and braking. Spaces 9 between the segments formingthethree belts result in rather long slots into which the teeth of adriving sprocket or idling sprocket project. These sprockets are notshown as they are standard in snowmobiles and their shape is not changedby the present invention. In other words, the slots formed by theopenings 9 permit the teeth of the sprocket to drive the beltspositively.

It will be apparent from a consideration of the figures that any onesegment can be removed if damaged and replaced without replacing thewhole of the belt or track. Similarly, tracks of various lengths forsnowmobiles of different design can be made up of standard segments toany desired length in segment multiples. It is, therefore, not necessaryto stock endless belts of lengths corresponding to eachsnowmobile.

FIG. 12, which uses segments of the same general design as in FIGS. 1 to3 but with uncleated surfaces on the cylinder, illustrates the formationof a square structure. It will be seen in FIG. 12 that this is made upof a number of sets of three segments, two being shown in the drawing.The pins 4 are much longer, and structures are formed which have aconsiderable amount of strength and are, of course, very light. They areuseful, for example, for certain antenna towers and the like and cangive and bend under strong winds and when suitably guyed possessconsiderable strength and protect against quite high winds. While inFIG. 12 there are only four segments, which might be thought of as veryshort belts, the construction is the same as in FIGS. 1 to 3; but ofcourse with the shortness the hinges turn through a very large angle, inthis case the maximum angle of approximately 90". This is another fieldof utility for the same general type of segment and is in addition tothe principal and at present mostimportant field of use, namelysnowmobile tracks, which are particularly shown in FIG. 2.

Reference has been made to reinforcements which can be provided in theflat segments if desired. This is illustrated in FIG. 3 in the brokenaway parts at 10 in the form of a molded in reinforcing fabric, forexample of Nylon or F iberglas cloth. In a similar manner, thereinforcements can be molded into a somewhat different design ofsegments shown in later figures and are illustrated specifically inbroken away portions in FIG. 6.

FIGS. 4 to 9 illustrate a different form of hinge, F 16s. 4 to 6 and 9being suitable for snowmobile tracks and FIGS. 7 and 8 conveyor belts.Essentially, the pin and cylinder construction forming hinges is similarto the old style of FIGS. I to 3 and 12, and the pins and their matingcylinders are designated with the same reference numerals although theshape is somewhat different. It will be seen best in FIG. 4 that thereare a larger number of short cylinders'3 and they are molded onto therelatively flatter sections 1 in a somewhat different manner so thatthey cannot bend as far. This is illustrated by FIG. 4 which shows aportion of a disassembled snowmobile track, and at the left it will beseen that'the hinges cannot bend very far. This is due to the structurewherein theabutting faces of the cylinders and sections aresubstantially flat, and the pins are within the perpendicular projectionof the abutting flat faces. It will be seen in FIG. 5, which illustratesa-portion of a snowmobile track, that the amount of bending of the hingeis negligible and that the flexibility of the elastomer is all that ispermitting the bending. For snowmobile tracks where the radius ofcurvature of driving or idler sprocket is quite large, this creates noproblem.

FIGS. 4 to 6 also illustrate-a different pin structure in which thereare no closed ends of the cylinders. Here the pins are held in byfriction. Again, as in FIG. 1, FIG. 4 is an exploded view showingthepins starting through the cylinders. In FIGS. 4 to 6 and 9 anotherfeature is illustrated, namely that of an additional rib 1] which givesadded traction for the snowmobile. The traction is not betteressentially thanin the tracks of FIGS. 1 to 3 but the segments are muchwider for the same amount of traction, and it is this greater width thatpermits more flexibility of each segment, which again is shown at theleft in FIG. 5. I

The'separate rib also permits a further modification, which isillustrated in FIG. 9, in which there are inserted carbide tipped studs12 in holes in the 'ribs. This permits better traction on ice, as hasbeen referred to above. In order to emphasize the studs more clearly, inFIG. 9 they are shown as protruding quite a distance above the surfaceof the elastomer, whereas normally, as is well known, in the case ofstudded snow tires they protrude but little above the elastomer sincethey do not have to be very long to grip the ice. However, if shown ashardly protruding at all, the drawing is less clear, and therefore inFIG. 9 the studs are shown as protruding an exaggerated amount.

FIG. 6 also illustrates another feature. In the spaces 9 between thebelts there are molded in ridges 13 which strengthen the sides andtherefore help in providing longer life as far as wear on the sprocketteeth is concerned. These ridges also increase the resistance tosideways slipping or skidding in snow and so perform a dual function.

FIGS. 7, 8 and 9 and illustrate a somewhat different type of belt withthe flat segments 1 extending all the way across the full width of thebelt. This type of belt is useful as a conveyor belt, as illustrated inFIG. 7, or a power transmission belt, as illustrated in FIG. 8.

An essential difference from the belts described in the precedingfigures, for example FIGS. 4 and 5, is that the ridges 11 are on theinside of the belt instead of the outside and so are the hollow portionsthrough which thev pins pass. As they are of essentially the same designand are performing a similar function, the hollow members through whichthe pins pass to form a hinge are given the same reference numerals asin the other figures. In a similar manner the pins 4 also carry the samereference numbers. In the belts in FIGS. 7 and 8, the ridges l1 and theridge formed by the hinge elements 2 and 3 in effect are somewhat widelyspaced teeth and they cooperate with a sprocket 14 of suitable design.This is shown in FIG. 8. In general, for conveyor and power belts thespacing between hinges may be somewhat less than where a snowmobiletrack is involved. This has the additional advantage that even thoughthe new style of belt does not have hinges that can turn through a largeangle, the belt is still more flexible at the hinge than in the middleof a segment; and therefore, where the hinges are somewhat more closelyspaced, the problem of sprockets of moderate diameter is not so acute.

The outer surface of power transmission belts is smooth, as is shown inFIG. 8. However, in the case of conveyor belts this is not always thecase. The belt, of course, in the new style has no openings at thehinges and, therefore, moderately fine material, such as sand, can beconveyed without falling through the belt. The question of thesmoothness of the conveyor belt outer surface, however, is involved inthe nature of the things being moved on the conveyor. For example, someconveyors are used for moving packages or containers to be filled whichmust periodically be held up or, in the case of packages, deflected fromthe conveyor, and so for this type of use a smooth outer surface isneeded so that the conveyor can move continuously and slide under thepackages or other things that are being conveyed. In some otheroperations reverse is true and a package or other material conveyed must'be held so that it will not turn or slide off the conveyor. In suchcase the belt may have either molded in suction cups or they may beinserted in holes in the belt. The suction cups may be of more flexibleand thinner elastomer. FIG. 7 shows at the left-hand side themodification with suction cups, at the righthand side the smoothsurface. Of course, a conveyor will usually have a uniform surface, thatis either all smooth or all with suction cups, but by showing bothvariants on the same figure of the drawing the number of drawings isreduced.

When handling finely divided materials, such as sand, ground cement, andthe like, it is often desirable to prevent material falling off theedges of the conveyor as it moves. This can be effected in conveyors ofthe present invention by a molded in lip or shoulder on the ends of eachsegment. This is not shown in FIGS. 7, 8 and 10 as such lips areillustrated at 13 on FIG. 6 and their repetition on FIGS. 6 and 7 wouldonly confuse the drawings. When dealing with a modification for ashelter, for example of the general shape of a Quonset hut, which isillustrated in FIG. 11, very long segments are sometimes desirable andthese are illustrated in FIG. 10 and 11. The structure starts on asuitable foundation or floor 16. Since the nature of the hinges and theflat segments are the same as in the other figures, they are given thesame reference numerals, although of course the segments are very muchlonger. Very long segments reinforcing ribs 17 are provided and theseare illustrated more to the left of the drawings. For shelter purposeswater tightness is of importance. For example, at the rooftree a softinsert 18 may be used which is T-shaped and fits into recesses 19sections which are pinned together. At the start suitable hollowelements 20 may be fastened to the floor or foundation and the firstsegments pinned to them. This is illustrated also near the left-handside of FIG. 1 1.

We claim:

6. A segmented belt or track suitable for operation in contact withparticulate matter on one side of the belt only comprising a pluralityof substantially equal length flat segments along the length of thetrack, each segment being provided with separated, mating, hollowelements on both transverse edges of the segment and the hollow elementsbeing unitarily cast of an elastomer and the hollow elements on the twoedges whereby the ed es of each segment formin the belt are hel againstdeflections up or own, thus preventing passage of particulate matterthrough the belt at the outer edges 2. A snowmobile track according toclaim 1 in which the hollow members project beyond the flat segments toform a traction ridge transversely of the belt.

3. A snowmobile track or belt according to claim 2 in which at least oneadditional transverse projecting ridge is cast across the flat portionsof the segments, the projection being on the same side as that of thehollow elements.

4. A snowmobile track according to claim 3 in which the segments are ofpolyurethane elastomer.

5. A snowmobile track according to claim 2 in which the segments are ofpolyurethane elastomer.

6. A belt or track according to claim 1 in which the flat portions ofthe segments are reinforced with embedded fibers or fabrics. 1

7. An endless belt according to claim 1 in which the projections of thehollow members are on the inside of the belt.

8. An endless belt according to claim 7 in which at least one transverserib is cast in the flat portion of the segment extending out onto theinside of the belt.

9. A conveyor belt according to claim 7 is which the outer surface issmooth and continuous.

10. A conveyor belt according to claim 7 in which the outer surface isprovided with friction elements.

11. A conveyor belt according to claim 10 in which the friction elementsare suction cups.

12. A belt or track according to claim 1 in which the flat segments forma belt with slots when they are pinned together and some of the hollowelements are of sufficient length to bridge the spaces between the flatsegment sections so that each segment is a unit and slots are formedbetween the portions of the flat segments.

13. A segmented snowmobile track according to claim 12 in which thehollow elements project on one side of the segments and form tractionridges transversely of the segments, the slots between the portions offlat parts of the segments being dimensioned to mate with snowmobiledriving sprockets.

14. A snowmobile track according to claim 13 in which the segments areof polyurethane elastomer.

15. A belt or track according to claim 14 in which the flat portions ofthe segments are reinforced with embedded fibers or fabrics.

16. A snowmobile track according to claim 13 in which the pins throughthe hollow members are of Nylon.

the outer edges of

2. A snowmobile track according to claim 1 in which the hollow membersproject beyond the flat segments to form a traction ridge transverselyof the belt.
 3. A snowmobile track or belt according to claim 2 in whichat least one additional transverse projecting ridge is cast across theflat portions of the segments, the projection being on the same side asthat of the hollow elements.
 4. A snowmobile track according to claim 3in which the segments are of polyurethane elastomer.
 5. A snowmobiletrack according to claim 2 in which the segments are of polyurethaneelastomer.
 6. A segmented belt or track suitable for operation incontact with particulate matter on one side of the belt only comprisinga plurality of substantially equal length flat segments along the lengthof the track, each segment being provided with separated, mating, hollowelements on both transverse edges of the segment and the hollow elementsbeing unitarily cast of an elastomer and the hollow elements on the twoedges mating, the hollow elements extending substantially out to theouter edges of the belt; the segments being fastened together by pinsthrough the hollow segments forming hinges, the hollow elements on theedges of the segments having substantially flat faces abutting directlyagainst opposite substantially flat faces of adjacent mating segmentssaid pins being within the perpendicular projection of said faces sothat when pinned the hinges cannot open to any substantial angle and theflexibility of the belt at the hinge is therefore determined primarilyonly by the flexibility of the elastomer forming the segments, wherebythe edges of each segment forming the outer edges of the belt are heldagainst deflections up Or down, thus preventing passage of particulatematter through the belt at the outer edges
 6. A belt or track accordingto claim 1 in which the flat portions of the segments are reinforcedwith embedded fibers or fabrics.
 7. An endless belt according to claim 1in which the projections of the hollow members are on the inside of thebelt.
 8. An endless belt according to claim 7 in which at least onetransverse rib is cast in the flat portion of the segment extending outonto the inside of the belt.
 9. A conveyor belt according to claim 7 iswhich the outer surface is smooth and continuous.
 10. A conveyor beltaccording to claim 7 in which the outer surface is provided withfriction elements.
 11. A conveyor belt according to claim 10 in whichthe friction elements are suction cups.
 12. A belt or track according toclaim 1 in which the flat segments form a belt with slots when they arepinned together and some of the hollow elements are of sufficient lengthto bridge the spaces between the flat segment sections so that eachsegment is a unit and slots are formed between the portions of the flatsegments.
 13. A segmented snowmobile track according to claim 12 inwhich the hollow elements project on one side of the segments and formtraction ridges transversely of the segments, the slots between theportions of flat parts of the segments being dimensioned to mate withsnowmobile driving sprockets.
 14. A snowmobile track according to claim13 in which the segments are of polyurethane elastomer.
 15. A belt ortrack according to claim 14 in which the flat portions of the segmentsare reinforced with embedded fibers or fabrics.
 16. A snowmobile trackaccording to claim 13 in which the pins through the hollow members areof Nylon.